"You are making good progress. The problem with using RMS values is that unless the load is purely resistive, you must know the power factor for the load you are driving. This is usually unavailable or so inaccurate as to be useless."
Yeah I talk about that some in the section on accuracy. If you scroll down to my comparison chart from this link - http://jarv.org/pwrmon.shtml#accuracy you can see the power-factor for the computer is 0.64 where the power factor for the purely resistive loads are closer to 1. This obviously makes a huge difference for individual devices, does it matter much for the aggregate? Not sure, for now i'm approximating my power factor to be relatively constant for my total power consumption.
I thought about hooking up a transformer for both phases and monitor voltage in parallel to current. I was looking over ladyada's kill-a-watt hack (Tweet-a-Watt! A safe and simple wireless power monitor) and saw that it's possible to grab a voltage waveform from the device although I'm not how it is adjusted prior, maybe I'll look into that.
Thanks for the link!